When producing an oil or gas well it is desirable to control the fluid flow into or out of the production tubular, for example, to balance inflow or outflow of fluids along the length of the well. For instance, some horizontal wells have issues with a heel and toe effect, where differences in pressure or the amount of the various fluids that are present at a particular location can lead to premature gas or water breakthrough significantly reducing the production from the reservoir. Inflow control devices have been positioned in the completion string at the heel of the well to stimulate inflow at the toe and balance fluid inflow along the length of the well. In another example, different zones of the formation accessed by the well can produce at different rates. Inflow control devices may be placed in the completion string to reduce production from high producing zones, and thus stimulate production from low or non-producing zones. In some instances a sliding sleeve or other valve may be placed in a well where there is a significant pressure differential between a first side of the valve and another side of the valve requiring significance amount of power to open or close the valve.
In line with the need to control the flow of fluids into or out of an oil and gas well it may be desirable to have partial flow positions controllable at any position from fully open to fully closed and all positions between. Such control and in particular partial flow positions typically require relatively substantial amounts of power to overcome the inertia of the valve, corrosion, debris in the valve shift path, or most usually the high relative pressure differentials that exist within a well. Unfortunately most wells are located in remote locations or at extreme distances downhole where high power circuits, such as electrical or hydraulic, are not available.